Hitherto, there have been used electronic equipment, such as, for example, a disc recording and/or reproducing apparatus or a tape recording and/or reproducing apparatus, etc. for carrying out recording and/or reproduction of information signals with respect to a recording medium such as an optical disc or a magnetic tape, etc. on which information signals are recorded.
In the electronic equipment of this kind, electronic equipment caused to be of compact structure so that they can be used exclusively in a carrying (portable) manner are widely used. In these electronic equipment used in a carrying (portable) manner, even in the case where a user inadvertently falls when he is carrying it, or any impact is applied thereto, it is strongly required to securely protect the recording and/or reproduction unit and/or other mechanical parts accommodated within the casing.
In view of the above, in order to guarantee mechanical strength of the casing within which the recording and/or reproduction unit and/or other mechanical parts are accommodated, electronic equipment in which the casing is formed by metallic material are used. As metallic material constituting the casing, aluminum (Al) alloy, titanium (Ti) alloy, and zinc (Zn) alloy, etc. are used.
The casing formed by such metallic material as mentioned above is formed by implementing press-working (pressing) to aluminum alloy or titanium alloy in a thin plate form.
Moreover, in the casing formed by zinc alloy or aluminum alloy, the casing is formed by implementing die-cast molding to such metallic material.
Meanwhile, in the case where metallic plate material such as aluminum alloy or titanium alloy, etc. is used to carry out press-working to form a casing, it is impossible to integrally form supporting members for supporting the tape drive unit or the disc recording and/or reproduction unit and the circuit board which are accommodated within the casing, and/or fixing portions for attaching screws for fixing the above-mentioned components. In view of the above, in the case where the casing formed by pressing metallic plate material is used, there is prepared an attachment member formed by molding synthetic resin in a manner separate from the casing to attach the tape drive unit or the disc recording and/or reproduction unit, etc. through the attachment member. In this case, the casing is also fixed to the attachment member.
As stated above, in the case where the casing formed by press-working is used, an attachment member molded by synthetic resin is required. As a result, the number of parts constituting the equipment body is increased. Thus, the configuration becomes complicated.
Moreover, in the case where the casing is formed by die-cast molding zinc alloy or aluminum alloy, it is possible to form the attachment portion for attaching the tape drive unit or the disc recording and/or reproduction unit, etc. in a manner integral with the casing. Accordingly, the necessity of using separate attachment member is eliminated. Therefore, reduction of the number of parts can be realized. However, since weight of the casing becomes heavy (is increased), the weight of the equipment itself would be increased. Namely, since specific gravity of zinc is about 6.6, and even when aluminum which has relatively small specific gravity among metallic materials is used, its specific gravity is 2.7, in the case where metallic alloy of this kind is caused to undergo die-cast molding to integrally form attachment member, etc., the quantity of material used is also increased, resulting in heavy weight of the casing.
Accordingly, in the case where such a casing of large (heavy) weight is applied to electronic equipment used in a carrying (portable) manner, convenience of the portability is adversely affect.
In the case where a speaker unit is caused to be included within a casing as described above, since it is impossible to sufficiently absorb vibration produced when the speaker unit is driven, it becomes difficult to obtain reproduction sound having satisfactory or excellent sound quality. Namely, in the case where the speaker unit is attached through the attachment member to the metallic casing, it is difficult to firmly fix the speaker unit to the casing. Accordingly, in the case where the speaker unit is driven, any unnecessary vibration takes place, resulting in deteriorated sound quality. In electronic equipment in which the attachment member for attaching the speaker unit, etc. is disposed within the casing, since it is difficult to constitute space sufficient to attenuate sound radiated from the back of the speaker unit within the casing, it is difficult to realize satisfactory reproduction characteristics.
In addition, in the case where the casing formed by die-cast molding zinc alloy or aluminum alloy is used, it is possible to directly attach the speaker unit to the casing. However, since vibration of the speaker unit cannot be sufficiently absorbed by the casing, any unnecessary vibration takes place, thus failing to obtain satisfactory reproduction characteristic.